Data center developers are expected to spend as much as $4 trillion by the end of the decade — and they’re already heavily constrained by both political and power-grid considerations in where they can build. But while most treat the speed of fiber as a given, one company is betting that faster fiber could change the geographical math behind the data center buildout. On Tuesday, Relativity Networks announced $22 million in SAFE note funding drawn by Rhapsody Venture Partners, Bell Ventures Inc. , and Faster Than Glass LLC, among others.
A SAFE note, in which an investment transfers into a specific numbers of shares once the company raises its first priced round, is a standard method used for pre-seed and seed rounds. The company also secured a $40 million follow-on order from a leading hyperscaler that declined to be named for this piece. Relativity Networks deals in hollow-core fiber, a rarely deployed technology that allows data to be transmitted 30% faster than conventional fiber.
Where traditional fiber transmits light through fiber-optic glass, hollow-core fiber transmits the same light through a vacuum chamber in the center of the line, bringing it far closer to the theoretical limit of light speed. The difference is a matter of microseconds. CEO Jason Eisenholz estimates that a signal takes roughly five microseconds to travel one kilometer in conventional fiber. By switching to hollow-core, that figure can be reduced to only three and a half microseconds.
When AI compute occurred across a single rack of GPUs, the fiber latency was easy to ignore - but as scale has grown, so has the physical distance between GPUs. Now, it’s common for a data center campus to sprawl across hundreds of acres and dozens of buildings. Eisenholz sees a particular opportunity for multi-campus deployments, in which pre-existing data centers are knit together to operate as a single unit. “The largest systems are distributing the compute across multiple campuses to reach the power that exists,” he tells TechCrunch.